First light for SiFAP2 at the TNG

The TNG staff in collaboration with the INAF-IAPS Roma, Univ. of La
Sapienza, INAF- Rome Astronomical Observatory and the University of Catania
successfully obtained the first light for the new improved version of the
Silicon Fast Astronomical Photometer and Polarizer (SiFAP2).
The Pulsar of the Crab Nebula (M1) and several other objects have been
observed with SiFAP2 mounted as Visiting Instrument at the Nasmyth-A F/11
focal plane of the Telescopio Nazionale Galileo on the night of Nov, 14th
2018.

SiFAP2 allows for fast timing detection of variable objects at sampling of
up to 25 nanoseconds thanks to a custom readout electronics developed by F.
Ambrosino and F. Meddi at La Sapienza. The previous version of the
photometer (SiFAP) has already shown its capabilities at the TNG allowing
the First detection of optical pulsations from a transitional ms pulsar
(F. Ambrosino, A. Papitto, L. Stella et al. Nature Astronomy 1, 854, 2017).
The new improved version of the optomechanical system, developed at the
FGG by A.Ghedina and the FGG Technology and IT Divisions, in collaboration
with F.Leone from Univ. of Catania, gives more versatility to the photometer
and a new polarimetric observing mode. Three MPPCs from Hamamatsu with ~50
arcsec2 FoV receive the light from the TNG and can observe the target and
a reference star in simple photometry or with linear and circular
polarimetry. The system allows for easier pointing on the sky and fast
switch between the observing modes. A set of Johnson and Sloan broadband
filters is also available. The system is described in “SiFAP2: a new
versatile configuration at the TNG for the MPPC based photometer”
A. Ghedina, F. Leone, F. Ambrosino et al. ,SPIE proc. 107025Q (2018).

The capabilities of SiFAP2 clearly show the opportunity to consider it as
a niche instrument for Time Domain Astronomy. The TNG staff is evaluating
both the option to use SiFAP2 as follow-up and the possibility to offer it
as PI instrument in the next calls.

Illustration 1: SiFAP2 is installed at the direct F/11 Nasmyth focus of
the TNG telescope and takes advantage of the previously mounted filter
wheel of the decomissioned OIG. The detector used for Reference can be
moved radially off-axis from the Target to cover a FoV between 3.6 and
8.3 arcmins into which search for the reference star. The position angle
is changed by moving the derotator.

Illustration 2: A screenshot of the GUI of one of the MPPC with the real
time counts of photons from the Crab Pulsar during first light of SiFAP2.
The 20 seconds plot shows one point every 100ms with 1ms gate.

Illustration 3: Massimo Cecconi (left), Adriano Ghedina (right) and
Filippo Ambrosino (remotely connected from Rome) celebrating the first
light of SiFAP2 at the TNG. The two TNG observers had to cheers and
drink also for F.Ambrosino, F.Meddi, A.Papitto, F.Leone and all the
rest of the FGG staff who could not participate at the observing run.